Chip coated light emitting diode package and manufacturing method thereof

ABSTRACT

A chip coated LED package and a manufacturing method thereof. The chip coated LED package includes a light emitting chip composed of a chip die-attached on a submount and a resin layer uniformly covering an outer surface of the chip die. The chip coated LED package also includes an electrode part electrically connected by metal wires with at least one bump ball exposed through an upper surface of the resin layer. The chip coated LED package further includes a package body having the electrode part and the light emitting chip mounted thereon. The invention improves light efficiency by preventing difference in color temperature according to irradiation angles, increases a yield, miniaturizes the package, and accommodates mass production.

CLAIM OF PRIORITY

This application claims the benefit of Korean Patent Application No.2006-0002829 filed on Jan. 10, 2006, in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a chip coated Light Emitting Diode(LED) package and a manufacturing method thereof and, more particularly,to a chip coated LED package which increases light extractionefficiency, accommodates miniaturization of a product and reducesmanufacturing costs, and to a manufacturing method thereof.

2. Description of the Related Art

In general, a Light Emitting Diode (hereinafter referred to as ‘LED’) isan electric component which converts electric energy to light energyfrom recombination of minority carriers (electrons and holes) injectedthrough a p-n junction structure of semiconductor and thereby emits thelight. That is, when a forward voltage is applied to a semiconductor ofa particular element, electrons and holes migrate through the junctionof an anode and a cathode and recombine with each other. The recombinedstate has a smaller energy than when the electrons and the holes areseparated from each other. Using this difference in energy, the LEDemits light.

The range of light generated from the LED is from a red region (630 nmto 780 nm) to a blue-Ultraviolet region (350 nm) including blue, greenand white. As the LEDs have advantages such as low power consumption,high efficiency, prolonged operation and lifetime, the demand thereforhas been increasing.

In addition, the range of application of the LEDs has been expanded fromsmall-sized illumination of mobile terminals to indoor/outdoorillumination, automobile illumination and backlights for large-sizedLiquid-Crystal Displays (LCDs).

FIG. 1 is a longitudinal sectional view illustrating a conventional LEDpackage. As shown, the conventional LED package 10 includes a packagebody 11 having an upwardly-open cavity formed therein, a lead frame 12.provided integrally to the package body 11, a light emitting chip 14,which is a light emission source for generating light when power isapplied, wired bonded by a plurality of metal wires 15 so as to beelectrically connected to the lead frame 12 and a transparent resinencapsulant 17 filled in the cavity to protect the light emitting chipand the metal wires from the outside environment.

The transparent resin encapsulant 17 is made of a transparent resin suchas epoxy to pass the generated light to the outside.

In the meantime, in a case where the light emitting chip 14 is providedas a blue light emitting device, a fluorescent material is included inthe transparent resin encapsulant 17 to obtain desired white light.

Such a fluorescent material is a wavelength-converting means thatconverts a first wavelength of blue light emitted from the lightemitting chip 14 to a second wavelength of white light. The fluorescentmaterial is made of Yitrium Aluminum Garnett (YAG)-based, TerbiumAluminum Garnett (TAG)-based, or silicate-based powder, and is mixed inthe transparent resin, the main substance of the transparent resin part17.

However, in the process of irradiating the blue light generated from thelight emitting chip 14 to the outside, beams of the blue light propagatefor different lengths before being converted into white light due to thestructure of the transparent resin encapsulant 17 containing thefluorescent material. This adversely causes non-uniform colortemperature according to the irradiation angles of white light.

Moreover, in this structure, the light emitting chip 14 and the metalwires 15 come in contact with the YAG-based, TAG-based andSilicate-based fluorescent material contained in the transparent resinencapsulant 17. Thus, made of heavy metal-based powder having electricconductivity, the YAG-based, TAG-based and Silicate-based fluorescentmaterial may cause leakage current degrading the light efficiency of thelight emitting chip 14 during light emission, ultimately undermining thereliability of the package.

Therefore, as an approach to prevent leakage current due to the contactbetween the fluorescent material contained in the transparent resinencapsulant and the metal wires 15, the light emitting chip 14 isflip-chip bonded on a submount (not shown) via a plurality of bumpballs, the submount is mounted on the lead frame 12 of the package body11, and the submount and the lead frame 12 are wire bonded by the metalwires so as to be electrically connected to each other.

Then, the transparent resin containing the fluorescent material isfilled in the cavity of the package body 11 or is applied to cover onlythe light emitting chip 14 flip chip bonded on the submount, therebyforming the transparent resin encapsulant 17.

However, in this structure of wire bonding the submount having the lightemitting chip 14 mounted thereon with the lead frame 12, it is necessaryto ensure a sufficient size of the submount to which the ends of themetal wires are bonded. This limits miniaturization of the package,complicates the manufacturing process and increases the manufacturingcosts.

SUMMARY OF THE INVENTION

The present invention has been made to solve the foregoing problems ofthe prior art and therefore an aspect of the present invention is toprovide a chip coated Light Emitting Diode (LED) package which canimprove light efficiency by preventing differences in color temperatureaccording to irradiation angles, increase a yield, and allowsminiaturization and accommodate mass production, and a manufacturingmethod thereof.

According to an aspect of the invention, the invention provides a chipcoated Light Emitting Diode (LED) package. The LED package includes: alight emitting chip including a chip die attached to a submount and aresin layer covering an outer surface of the chip die; at least one bumpball provided on the chip die and exposed through an upper surface ofthe resin layer and an electrode part electrically connected to the atleast one bump ball by a metal wire; and a package body having theelectrode part and the light emitting chip mounted thereon.

Preferably, the resin layer contains a fluorescent material forconverting the light generated from the chip die.

Preferably, the electrode part is provided as a lead frame integrallyprovided to the package body.

Preferably, the package body is a resin structure which is injectionmolded with resin to have a cavity formed therein, the cavity forexposing the electrode part with the light emitting chip mountedthereon.

More preferably, the cavity includes a reflecting part formed on aninner surface thereof for reflecting the light generated from the lightemitting chip.

More preferably, the cavity includes a filler made of transparent resinfilled therein and the package body further includes a lens provided onan upper part thereof.

Preferably, the package body has a disposition hole formed therein, thedisposition hole exposing a metallic chassis with the light emittingchip mounted thereon, and the package body is provided as a substratehaving the electrode part pattern-printed on an upper surface thereof.

More preferably, the disposition hole includes a reflecting part formedon an inner surface thereof for reflecting the light generated from thelight emitting chip.

More preferably, the disposition hole includes a filler made oftransparent resin filled therein and the package body further includes alens provided on an upper part thereof.

According to another aspect of the invention, the invention provides amethod of manufacturing a chip coated Light Emitting Diode (LED)package. The method includes: die attaching a plurality of chip dies ona wafer; providing at least one bump ball on an upper surface of each ofthe chip dies; forming a resin layer to cover the chip dies includingthe bump balls; polishing an upper surface of the resin layer to exposethe bump balls; and cutting the wafer and the resin between the chipdies into individual light emitting chips.

Preferably, the step of forming a resin layer includes printing a resinmaterial on the wafer to cover the chip dies including the bump ballsand thermally curing the printed resin layer.

Preferably, the resin layer is made of a resin material containing afluorescent material for converting the wavelength of light generatedfrom the chip dies.

Preferably, the method further includes: mounting each of the lightemitting chips composed of the chip die mounted on a submount and theresin layer covering an outer surface of the chip die on an electrodepart of a package body formed by injection molding to have anupward-opening cavity, and wire bonding the light emitting chip with theelectrode part provided as a lead frame by a metal wire.

Preferably, the method further includes: mounting each of the lightemitting chips composed of a chip die mounted on a submount and a resinlayer covering an outer surface of the chip die on an upper surface of ametallic chassis, and wire bonding the light emitting chip with theelectrode part provided as an electrode pattern formed on an uppersurface of the package body having a disposition hole formed therein,the disposition hole exposing the light emitting diode chip, by a metalwire.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a longitudinal sectional view illustrating a conventional LEDpackage;

FIG. 2(a) to (f) is a view illustrating a manufacturing process of anLED package according to the present invention;

FIG. 3 is a perspective view illustrating a chip coated LED packageaccording to a first embodiment of the present invention; and

FIG. 4 is a sectional view illustrating a chip coated LED packageaccording to a second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Exemplary embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

FIG. 2(a) to (f) is a view illustrating the fabrication of a chip coatedLED package according to the present invention and FIG. 3 is aperspective view illustrating a chip coated LED package according to afirst embodiment of the present invention.

The LED package 100 according to the present invention includes a lightemitting chip 110, an electrode part 120 and a package body 130.

The light emitting chip 110 includes a chip die 101, a bump ball 102, aresin layer 103 and a submount 104. The chip die 101, which isdie-attached on the submount 104, is a light emitting source forgenerating light when power is applied.

Here, the chip die 101 is a light emitting source for generating nearultraviolet rays or blue light when power is applied. For such a chipdie 101, it is preferable to use a gallium nitride-based light emittingdiode chip which generates blue light with high output and highluminance. The chip die 101 can adopt a horizontal structure in whichboth p- and n-electrodes are formed on an upper surface thereof or avertical structure in which p- and n-electrodes are. formed on upper andlower surfaces thereof, respectively.

In addition, the gallium nitride-based light emitting diode chip is awell-known semiconductor device, and thus an explanation on the specificconfiguration thereof is omitted.

The chip die 101, which is mounted on the submount 104, has a bump ball102 provided on an upper surface thereof. The bump ball 102 iselectrically connected to the electrode part 120. There may be provideda single bump ball 102 or two bump balls 102 depending on the structureof the chip die 101.

That is, the number of bump balls 102 varies depending on the structureof the chip die 101. If the chip die 101 has a vertical structure withthe p- and n-electrodes formed on upper and lower surfaces,respectively, there may be provided a single bump ball 102 whichelectrically connected to the p-electrode formed on an upper surface ofthe chip die 101.

If the chip die 101 has a horizontal structure with the p- andn-electrodes both formed on an upper surface thereof, there may beprovided two bump balls 102, each electrically connected to each of thep- and n-electrodes formed on an upper surface of the chip die 101.

In addition, the resin layer 103 is made of a transparent resin materialsuch as epoxy and silicone that covers an outer surface of the chip die101 die-attached on the submount 104.

Here, the resin layer 103 contains fluorescent material, a means forconverting the wavelength, one selected from the group consisting ofYAG-based, TAG-based and Silicate-based materials, capable of convertingthe light generated from the chip die into white light.

In addition, the electrode part 120 is electrically connected to atleast one bump ball 102 exposed through an upper surface of the resinlayer 103, by a metal wire 125.

As shown in FIG. 3, such an electrode part 120 may provided as a leadframe 121 which is integrally provided to the package body 130, aninjection-molded resin structure, and wire bonded with an end of themetal wire 125 having the other end connected to the bump ball 102. Thishowever does not limit the present invention, and as shown in FIG. 4,the electrode part 120 may also be provided as an electrode pattern 122printed on an upper, surface of the substrate 131 constituting thepackage body 130.

In addition, as shown in FIG. 3, the package body 130 with the lightemitting chip 110 electrically connected to the electrode part 120 is aresin structure injection molded with resin to have a cavity C whichhouses and exposes the electrode part 120 provided as the lead frame 121to have the light emitting chip 110 mounted thereon.

Such a cavity C includes a reflecting part 135 formed on an innersurface thereof so as to reflect the light generated from the lightemitting chip 110. The reflecting part 135 can be formed by evenlycoating or depositing a reflecting material made of one selected fromthe group consisting of Al, Pt, Ti, Cr and Cu having high reflectivityon an entire inclined inner surface of the cavity C. This however doesnot limit the present invention, and the reflecting part 135 may also beformed by separately attaching a sheet or film made of one selected fromthe group consisting of Al, Ag, PT, Ti, Cr and Cu having highreflectivity.

In addition, the package body 130 may have a lens L provided on an upperpart thereof to widen the beam angle of light generated from the lightemitting chip 110 or increase light efficiency. The cavity C enclosed bythe lens L may be filled with a filler made of transparent resin so asto protect the light emitting chip 110 and the metal wire 125 from theoutside environment.

In the meantime, FIG. 4 illustrates a chip coated LED package accordingto a second embodiment of the present invention. In this embodiment, thepackage body 130 of the LED package 100 a may include a metal chassis132 with the light emitting chip 110 mounted thereon and a substrate 131having a predetermined dimension of disposition hole 133 for exposingthe light emitting chip 110 and having the electrode part 120 patternprinted on an upper surface thereof.

Here, the disposition hole 133 may also have a reflecting part 135 forreflecting the light generated from the light emitting chip 110.

In addition, the package body 130 provided in the form of a substratecan also have a lens L provided on an upper part thereof in order towiden the beam angle of light generated from the light emitting chip 110or increase the light efficiency. A filler made of a transparent resinis filled in the space of the disposition hole 133 enclosed by the lensL.

As shown in FIG. 2(a), a manufacturing method of the LED package withthe above described configuration starts with die-attaching a pluralityof chip dies 101 manufactured by a semiconductor process on a wafer W.

Here, the wafer W may be made of non-conductive or conductive materialdepending on the arrangement of the p- and n-electrodes provided on thechip dies 101.

In addition, as shown in FIG. 2(b), at least one bump ball 102 isprovided on an upper surface of each of the chip dies 101 die-attachedon the wafer W.

There may be provided a single or two bump balls 102 can be provided inone or two depending on the arrangement of the p- and n-electrodes(horizontal or vertical type) on the chip dies 101.

It is preferable that the bump ball 102 is made of a metallic materialwith excellent thermal conductivity and electric conductivity, such asAu, Al and Cu.

Subsequently, as shown in FIG. 2(c), the step of forming a resin layer103 on the wafer W includes printing a transparent resin such assilicone and epoxy on the wafer W to cover the plurality of chip dies101 each with the bump ball 102 provided on an upper surface thereof.

At this time, the transparent resin is printed in a thickness of up to300 um considering the diameter of the bump ball 102.

In addition, the resin layer 103 printed on the wafer W to cover thechip dies 101 including the bump balls 102 is thermally cured byartificially provided heat.

Here, the resin layer 103 can contain a fluorescent material, awavelength-converting means, to convert the light emitted from the chipdies 101 into white light in accordance with the emission color of thechip dies 101.

In addition, as shown in FIG. 2(d), an upper surface of the resin layer103 provided on the wafer W is polished by a polishing means (not shown)to expose the bump balls 102 provided on the chip dies 101. Thepolishing method can be selected in consideration of precision andproductivity, such as using a grinder or cutting with a fly cutter.

At this time, the upper surface of the resin layer 103 should bepolished by the polishing means in a uniform thickness in parallel withthe surface of the wafer W.

Subsequently, as shown in FIG. 2(e), the wafer W with the chip dies 101and the resin layer 103 polished to expose the bump balls 102 is cutalong horizontal and vertical cut lines between the adjacent chip dies101 and separated into light emitting chips 110 generating light whenpower is applied.

Such a light emitting chip 110 is composed of a die-attached chip die101 provided on a submount cut out of the wafer W, at least one bumpball 102 provided on an upper surface of the chip die 101 and a resinlayer 103 exposing the bump ball 102 and uniformly covering an outersurface of the chip die 101.

As shown in FIG. 2 (f), the light emitting chip 110 with the aboveconfiguration is mounted on an upper surface of the electrode part 120provided as a lead frame 121, and the electrode part 120 is wire bondedto an end of the metal wire 125 having the other end bonded to the bumpball 102 of the light emitting chip 110.

Here, the electrode part 120 is a metallic member exposed through thecavity C of the package body 130 injection molded with resin to have theupward-opening cavity.

When a forward current is applied to the LED packages 100 and 100 a withthe above described configurations, the light emitting chip 110 issupplied with current via the electrode part 120, and thereby the chipdie 101 of the light emitting chip 110 emits light in a color out of RedR, Green G and Blue B depending on the material of the semiconductorconstituting the chip die 101.

In addition, the light generated from the chip die 101 is emitted viathe resin layer 103, provided to uniformly cover an outer surface of thechip die 101, to the outside.

At this time, in a case where the resin layer 103 contains a fluorescentmaterial, a first wavelength of the blue light generated from the chipdie is converted to a second wavelength of white light by thefluorescent material, allowing the light emitting chip 110 to generatewhite light.

Here, the resin layer 103 containing the fluorescent material isprovided in a uniform thickness over an outer surface of the chip diesuch that the light generated from the chip die 101 in response to powerapplication has a uniform path passing through the resin layer 103regardless of the irradiation angles, preventing the difference in colortemperature according to the irradiation angles.

In addition, the metal wire 125 is prevented from contacting thefluorescent material made of heavy metal having an electricconductivity, thereby preventing leakage current. This improves thelight efficiency of the light emitting chip 110 and preventsdeterioration of the thermal characteristics, ultimately improving theproduct reliability.

Further, the light generated from the light emitting chip 110 isreflected by the reflecting part 135 provided on an inner surfaces ofthe cavity C or the disposition hole 133, thus emitted in a wider angleto the outside.

According to the present invention set forth above, a resin layercontaining a fluorescent material is provided in a uniform thicknessover an outer surface of a chip die generating light in response topower application. In addition, a bump ball exposed out of the resinlayer is electrically connected to an electrode part by a metal wire.This allows the light passing through the resin layer to have a uniformpath irrespective of irradiation angles, preventing difference in colortemperature according to the irradiation angles, thereby improving lightefficiency.

In addition, the fluorescent material having an electric conductivity isprevented from contacting the metal wire, preventing leakage currentexhibited in the prior art, thereby improving product reliability.

Furthermore, the invention allows reducing the size of the package toachieve miniaturization, mass producing with a simple manufacturingprocess, and reducing the manufacturing costs.

While the present invention has been shown and described in connectionwith the exemplary embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

1. A chip coated Light Emitting Diode (LED) package comprising: a lightemitting chip including a chip die attached to a submount and a resinlayer covering an outer surface of the chip die; at least one bump ballprovide d on the chip die and exposed through an upper surface of theresin layer and an electrode part electrically connected to the at leastone bump ball by a metal wire; and a package body having the electrodepart and the light emitting chip mounted thereon.
 2. The chip coated LEDpackage according to claim 1, wherein the resin layer contains afluorescent material for converting the wavelength of light generatedfrom the chip die.
 3. The chip coated LED package according to claim 1,wherein the electrode part comprises a lead frame integrally provided tothe package body.
 4. The chip coated LED package according to claim 1,wherein the package body comprises a resin structure which is injectionmolded with resin to have a cavity formed therein, the cavity forexposing the electrode part with the light emitting chip mountedthereon.
 5. The chip coated LED package according to claim 4, whereinthe cavity comprises a reflecting part formed on an inner surfacethereof for reflecting the light generated from the light emitting chip.6. The chip coated LED package according to claim 4, wherein the cavitycomprises a filler made of transparent resin filled therein and thepackage body further comprises a lens provided on an upper part thereof.7. The chip coated LED package according to claim 1, wherein the packagebody has a disposition hole formed therein, the disposition holeexposing a metallic chassis with the light emitting chip mountedthereon, and the package body comprises a substrate having the electrodepart pattern-printed on an upper surface thereof.
 8. The chip coated LEDpackage according to claim 7, wherein the disposition hole comprises areflecting part formed on an inner surface thereof for reflecting thelight generated from the light emitting chip.
 9. The chip coated LEDpackage according to claim 7, wherein the disposition hole comprises afiller made of transparent resin filled therein and the package bodyfurther comprises a lens provided on an upper part thereof.
 10. A methodof manufacturing a chip coated Light Emitting Diode (LED) packagecomprising: die-attaching a plurality of chip dies on a wafer; providingat least one bump ball on an upper surface of each of the chip dies;forming a resin layer to cover the chip dies including the bump balls;polishing an upper surface of the resin layer to expose the bump balls;and cutting the wafer and the resin layer between the chip dies intoindividual light emitting chips.
 11. The method according to claim 10,wherein the step of forming a resin layer comprises printing a resinmaterial on the wafer to cover the chip dies including the bump ballsand thermally curing the printed resin layer.
 12. The method accordingto claim 10, wherein the resin layer is made of a resin materialcontaining a fluorescent material for converting the wavelength of lightgenerated from the chip dies.
 13. The method according to claim 10,further comprising: mounting each of the light emitting chips comprisingthe chip die mounted on a submount and the resin layer covering an outersurface of the chip die on an electrode part of a package body formed byinjection molding to have an upward-opening cavity, and wire bonding thelight emitting chip with the electrode part comprising a lead frame by ametal wire.
 14. The method according to claim 10, further comprising:mounting each of the light emitting chips comprising a chip die mountedon a submount and a resin layer covering an outer surface of the chipdie on an upper surface of a metallic chassis, and wire bonding-thelight emitting chip with the electrode part comprising an electrodepattern formed on an upper surface of the package body having adisposition hole formed therein, the disposition hole exposing the lightemitting diode chip, by a metal wire.